An analysis of the key drivers of the Japanese digital therapeutics patents: A cross‐sectional study

Abstract Background Digital therapeutics (DTx) are software or other tools that support or implement medical practices such as disease prevention, diagnosis, and treatment using digital technology. DTx has been approved in Japan, and it is anticipated that the number of approvals will increase in the future. DTx differs from conventional medical devices in that its primary purpose is treatment. Aim This study aims to identify the key drivers of DTx in Japan by analyzing patents in the field of medical information, including DTx. Methodology This study visualizes the results of patent analyses for DTx and examines patent applications that feature applied technology and indications in the medical information field as the key drivers. The study will also employ patent citation analysis. It can be argued that the more citations a patent receives, the more similar research and development activities are being conducted, and the greater the competition. The number of citations per patent application will also be calculated to help identify areas where the value per patent application is high and competition intensifies. A patent citation matrix analysis will be conducted for notable Japanese companies in the DTx field. The citation matrix analysis consists of the number of citations and the company's selfcitation ratio to visualize the patent value. This study investigates the key drivers of DTx by analyzing patent technologies, focusing on patent applications with a high number of citations or a high selfcitation ratio. Results Key drivers of digital therapeutics were examined by analyzing patents in the fields of healthcare informatics and diagnostics. In terms of the number of patent applications and citations in Japan, numerous patents were related to “applications,” “sensors,” “medical imaging,” “central nervous system/psychiatry,” and “heart.” As a result, Japanese companies are expected to conduct R&D with an eye toward overseas expansion.


| INTRODUCTION
Digital Therapeutics, also known as DTx, are software or other tools that support or implement medical practices such as disease prevention, diagnosis, and treatment using digital technology.
On June 19, 2020, Cure-Up and Keio University School of Medicine developed an antismoking system that includes an analyzer to measure carbon monoxide concentration in exhaled breath and a medical device program that assists smoking cessation treatment by encouraging behavioral changes. The company was approved to manufacture and sell the system as a medical device. Other applications include a platform to improve the lifestyle of diabetes patients (Mitsubishi Tanabe Pharma Corporation), an application to treat major depressive disorder (MDD) (Otsuka Pharmaceutical/Click Therapeutics), an application to treat attention deficit hyperactivity disorder (ADHD) (Shionogi Pharmaceutical Co./Akili Interactive Inc.), and others in development.
In addition, related patents have been filed globally to protect the intellectual property resulting from the development of these digital therapies.
The purpose of this study is to examine the key drivers of digital therapy by analyzing patents in the fields of healthcare informatics and diagnostics, including digital therapy (medical information field). The key drivers are defined as keywords promoting the development of DTx.
The key drivers of digital therapy will be extracted in terms of applicable technologies and indications in the medical information field.

| METHOD
The key drivers are defined as keywords promoting the development of DTx. The key drivers of digital therapy will be extracted in terms of applicable technologies and indications in the medical information field using the International Patent Classification (IPC) of 2021, which creates a hierarchical system of language-independent symbols for the classification of patents and utility models according to different technical fields. We collected patent data using the patent database provided by Panasonic and identified existing DTx technologies and candidate technologies for DTx. Even if patents have common IPC codes, they can be classified into similar technologies. Based on text information, we extracted the keywords of DTx technologies and candidate technologies associated with each keyword.
As shown in Figure 1, the methods of Patent Application Analysis (Time Series Analysis), Citation Analysis, and Patent Technology Analysis are employed in this study through keyword extraction based on data from IPC, IPC description, applicant, filing date, citation, and patent description of patent databases.

| Patent application analysis (time series analysis)
This study will visualize the results of the patent analysis of digital therapy and analyze patent applications in the field of medical information, using applied technology and indications as key drivers to examine the key drivers of digital therapy. The visualization of the patent analysis will be conducted through quantitative analysis based on the patent information collected from the patent database. The patent database, provided by Panasonic, contains patent information published since 1971. 1 Furthermore, by analyzing information on patent applicants, it is possible to organize the rights relationship in joint research and development between medical institutions and companies.

| Citation analysis and citation matrix analysis
In this study, Patent Citation Analysis is also used. Patent citation analysis is a method that assumes that the higher the number of citations, the higher the value of the patent; however, it can also be said that the higher the number of citations, the greater the number of similar research and development projects, and the more intense the competition. The number of citations per patent application is also calculated. This will identify areas where the value per patent application is high and competition is intense. 2 In addition, a patent citation matrix analysis will be conducted on Japanese companies of interest in digital therapy. This is an application of the Boston Consulting Group's Product Portfolio Matrix (market growth and market share matrix) to the evaluation of patent value, and is composed of the number of citations (growth potential of patent value) and the company's citation ratio (technology share by the company), and can visualize patent value. 1 In this study, we extracted patent applications for digital therapy in Japan using the patent database and show trends in patent technology through citation and citation analysis.

| Patent technology analysis
This study will examine the key drivers of digital therapy by extracting characteristic patent applications through time series analysis, citation analysis, and citation matrix analysis, and analyzing patent technology by focusing on patent applications with a high number of citations or in-house citation ratio. To conduct a patent F I G U R E 1 Methods and process of the analysis. technology analysis, the applicant, title of invention, and abstract of the patent application will be presented.

| Patent application analysis (time series analysis)
To facilitate international use, patent documents are classified according to the IPC. The IPC analysis is conducted by extracting patents from databases and analyzing them statistically. The IPCs for technical fields that include digital therapy are "G16H" and "A61B." Here, IPC "G16H" is assigned to "Healthcare Informatics, that is, medical or health care information and communication technology particularly adapted to the handling or processing of data." IPC "A61B" includes "diagnosis, surgery, personal identification." A patent analysis website was used for the survey. The number of patent applications in the technical field (medical information field) corresponding to IPC "G16H" and "A61B"    Table 1 is a table showing the represented IPCs "G16H," "A61B," and others. If the technology field of the invention covers a wide range, more than one IPC may be assigned. IPCs other than "G16H" and "A61B" are also extracted in Figure 4. The IPCs are subdivided into more precise sections (Subclass). "A61B 5/00" indicates "Detection, measurement, recording, and identification for diagnosis." "G16H 10/60" indicates "Patient-specific data." "G06Q 50/22" indicates "Social welfare services." "G16H 50/20" indicates "Computer-aided diagnosis." "G06Q 50/24" indicates "Educational management or guidance." "G16H 50/30" indicates "Calculating health indicators, Individual health risk assessment." "G06F 19/00" indicates "Digital computing, Data processing apparatus or methods, Special applications." "G16H 40/63" indicates "Local operation." "A61B 5/11" indicates "Measuring movement of the whole body or parts thereof," and "A61B 6/00" indicates "Equipment for radiological diagnosis." The top patent filers include "Philips," "Toshiba," "Fujifilm," "Siemens," "Canon," "Samsung," and others. Note that "Toshiba" and "Toshiba Medical Systems" are counted as different applicants.

| Keyword extraction
In addition to the above IPCs, keywords are extracted to analyze patents containing specific keywords. The extraction of keywords utilizes the F-term, a technical classification unique to the JPO that focuses on the technical feature points of literature and is developed The number of patent applications indicating IPC "G16H" and "A61B." with computer searches in mind. First, major keywords were selected from the technical aspect of digital therapy and the indication or treatment site aspect. Then, explanations of F-terms containing the major keywords were searched, and minor keywords (subterms) were selected from the retrieved explanations. Table 2 shows the major and minor keywords that were extracted.
Frequently occurring words in patent applications assigned IPCs "G16H" and "A61B" are shown in Table 3. These frequently occurring words were also used as references for the extraction of subterm keywords.
IPC "G16H" and "A61B" as well as the above-mentioned  Table 11 shows the number of citations per patent application in Japan, with major term keywords as follows: Application (0.72), cardiac (0.68), blood vessel (0.45), artificial intelligence (0.36), allergy

| Patent technology analysis
We conducted a patent technology analysis on the top most cited Japanese patent applications by category (major term keywords). The patent technology analysis is conducted by referring to the applicant, the name of the invention, and the abstract (the source is the gazette number). [Title of invention] System and method for automated diagnosis and decision support for heart-related diseases and conditions.

| Patent technology analysis
[Summary] …to provide decision support for various aspects of a physician's workflow, including automated diagnosis of conditions such as heartrelated medical conditions……a CAD (computer-aided diagnosis) system for cardiac imaging and applications are provided. [Problem] To provide a stimulus presentation system that leads the user's psychological state to the target psychological state.
[Solution] The stimulus presentation system of the present disclosure is equipped with… a psychological state determination unit that determines whether or not the user has reached the target psychological state… based on the user's biometric information acquired after the presentation of the stimulus presentation contents has started.        Provide information processing equipment that easily evaluates the degree of recovery from fatigue before and after sleep….  …The device has multiple types of sensors, including a spectrometer and one or more of the following: accelerometer, heart rate sensor, blood pressure sensor, blood glucose sensor, sweat sensor, skin conduction sensor, or image sensor. The device processes… sensor data to determine the health status of the user.

| Summary of result
The results of the analysis of the number of patent applications, the number of citations, the number of citations per patent application, and the patented technologies are shown in Table 12. According to From the details of the IPC, the keywords "computing," "patient data," and "diagnostic radiology equipment" were found as applicable technologies, and "diagnosis" and "evaluation" as objectives.
Furthermore, in the medical information field, narrowing down the keywords in terms of applicable technologies and indications, in Japan, there were many patent applications corresponding to applicable technologies and indications related to "medical images," "prediction," "sensors," "central nervous system/mental," and "biological data." It can be assumed that research and development in the medical information field are actively conducted in these applicable technologies and indications.
In terms of the number of citations in the medical information field, it is considered that in Japan, a large number of highly valuable patent applications are filed in the fields of "medical imaging," "central Patented technology Technologies, applications, and user interfaces that analyze medical images and patient data and lead to diagnostic evaluations and target conditions nervous system/mental," "prediction," "biological data," "vascular," and "cardiac." Based on the number of citations per patent application in the medical information field, it can be assumed that in Japan, "apps," "cardiac," and "vascular" are most common, and the value per patent application is high in these applicable technologies and indications, and competition is intense.
As a result of the analysis of patent technologies with a large number of citations in the medical information field, in Japan, "technologies and applications related to technologies and user interfaces that analyze medical images and patient data and lead to diagnostic evaluation and target conditions" have a large number of citations and are considered to have high value. The technologies developed in Japan focus on data and user interfaces.
However, in the medical information field, there have been few patent applications for digital therapeutics for the direct purpose of disease prevention, diagnosis, and treatment, and they have been buried in many patent applications, making it difficult to distinguish between digital therapeutics and other medical information technologies.

| CONCLUSION
Key drivers of digital therapy were examined by analyzing patents in the fields of healthcare informatics and diagnosis (medical information field), using the applicable technologies and indications as key drivers.
In terms of the number of patent applications and citations in Japan, there were many patents related to "applications," "sensors," "medical imaging," "central nervous system/psychiatry," and "cardiac," indicating a common need in Japan. Therefore, Japanese companies are expected to conduct R&D with an eye to overseas expansion.
We suggest that Japanese companies have significant advantages and should utilize these technologies for DTx of the target disorders and pursue digital use-cases in the area as highly potential markets of DTx.
The data that support the findings of this study are available from the corresponding author upon reasonable request.

ACKNOWLEDGMENTS
The research was financially supported by the Japan Association for the Advancement of Medical Equipment.

CONFLICTS OF INTEREST STATEMENT
The authors, whose names are listed immediately below, certify that they have no affiliations with, or involvement in, any organization or entity with any financial interest (such as honoraria, educational grants, participation in speakers' bureaus, membership, employment, consultancies, stock ownership, or other equity interest, and expert testimony or patent-licensing arrangements) or nonfinancial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.

ETHICS STATEMENT
This manuscript has not been previously published and is not under consideration for publication elsewhere. We have adhered to ethical principles throughout the research process, including the appropriate use of data and citation of sources.

TRANSPARENCY STATEMENT
The lead author Tetsuaki Oda affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.